1. Field of the Invention
The present invention generally relates to mechanisms for inserting and removing electronic circuit units, and more particularly, to a mechanism for inserting and removing electronic circuit units for an electronic device, such as a communication device, an information processing apparatus, and a measurement apparatus, having a shelf where a large number of the electronic circuit units are installed.
2. Description of the Related Art
An electronic circuit unit is installed in a shelf of an electronic device, such as a communication device, an information processing apparatus, and a measurement apparatus. A lever for inserting and removing is rotatably attached to the electronic circuit unit. The electronic circuit unit is connected to a connector on the back board of the shelf by rotating the lever. The electronic circuit unit is locked with the shelf in order to connect the electronic circuit unit to the connector securely, so that a connection for electric signals is accomplished.
FIG. 1 is a view for explaining a conventional mechanism for inserting and removing electronic circuit units. FIG. 2 is an exploded perspective view of a lever 12 for inserting and removing.
Referring to FIGS. 1 and 2, electronic circuit units 10 are mounted on a shelf 20 having a box configuration. The electronic circuit unit 10 includes the levers 12 for inserting and removing, stoppers 13, and receiving parts 14. The levers 12 for inserting and removing are rotatably attached to upper and lower parts of the front end part of an electronic circuit board 11. The stopper 13 is attached to the lever 12 for inserting and removing so as to be rotated by a spring 19 shown in FIG. 2, wherein a pin 16 is the center of the rotation of the stopper 13. The stopper 13 is received by the receiving part 14. The mechanism for inserting and removing the electronic circuit unit 10 consists of the lever 12 for inserting and removing, the stopper 13, and the receiving part 14.
FIG. 3 is a view for explaining an insertion of the electronic circuit unit 10 shown in FIG. 1 to the shelf 20 and a lock operation. Since the mechanism for inserting and removing provided at an upper part of the front end part of the electronic circuit unit 10 acts substantially the same as the mechanism for inserting and removing provided at a lower part of the front end part of the electronic circuit unit 10, only the mechanism for inserting and removing provided at the lower part of the front end part of the electronic circuit unit 10 will be described and explanation of the mechanism for inserting and removing provided at the upper part of the front end part of the electronic circuit unit 10 will be omitted.
In a state shown in FIG. 3-(A), first the electronic circuit unit 10 shown in FIG. 1 is inserted to the shelf 20, and then the lever 12 for inserting and removing is rotated counterclockwise. A claw part 15 comes in contact with a frame 21 of the shelf 20. The lever 12 is rotated counterclockwise based on the leverage. And thereby, the stopper 13 comes in contact with the receiving part 14.
In a state shown in FIG. 3-(B), the lever 12 for inserting and removing is further rotated counterclockwise. The stopper 13 is rotated clockwise in a state where the pin 16 is the center of the rotation of the stopper 13, so that the stopper 13 is situated at an upper part of the receiving part 14.
In a state shown in FIG. 3-(C), the lever 12 for inserting and removing is further rotated counterclockwise, so that the electronic circuit unit 10 shown in FIG. 1 is further inserted to the shelf 20. The stopper 13 is situated on a concave part 17 of the receiving part 14, and thereby the stopper 13 is locked with the receiving part 14. In this case, a gap having a distance y between the right end of the frame 21 and the front end of the electronic circuit board 11 is made.
A surface board is provided to the electronic circuit unit 10. A shield gasket is provided around the surface board so as to shield against the leakage of an electromagnetic wave to the outside.
Meanwhile, recently, technology has progressed so that signals connected by the connector have a high frequency. Because of this, the length of a contact pin at the connection part of the connector has become short. Hence, it is required to make a secure connection between the connector of the electronic circuit unit and the connector of the back board.
However, the conventional mechanism for inserting and removing electronic circuit unit 10 has problems with regard to the connection of the connector.
First of all, the conventional mechanism for inserting and removing electronic circuit unit 10 has a backlash, namely play with respect to the lock by the lever 12 for inserting and removing. Hence, it is difficult to assure the connection of the connector securely.
That is, in a state shown in FIG. 3-(C), the stopper 13 is rotated clockwise wherein a pin 16 is the center of the rotation of the stopper 13, so that the stopper 13 is moved on the concave part 17 of the receiving part 14. And thereby, a gap having a distance X between a right end of the concave part 17 and the stopper 13 is made. Accordingly, in a state shown in FIG. 3-(C), if a force for pulling the electronic circuit unit 10 from the shelf 20 due to a vibration, for example, is applied to the electronic circuit unit 10, that is, if a force is applied to the electronic circuit unit 10 in an opposite direction to the insertion direction of the electronic circuit unit 10 to the shelf 20 (in a right side direction in FIG. 3-(C)), a state shown in FIG. 3-(D) occurs. That is, the gap having the distance X between the stopper 13 and the concave part 17 of the receiving part 14 is closed and the gap between the right end of the frame 21 and the front end of the electronic circuit board 11 is increased from the distance y to a distance y+z.
That means, even if the electronic circuit unit 10 shown in FIG. 1 is inserted to the shelf 20 and the stopper 13 is situated on the concave part 17 of the receiving part 14 so that the stopper 13 is locked with the receiving part 14 as shown in FIG. 3-(C), backlash, namely play having a distance Z with respect to the lock by the lever 12 occurs in the conventional mechanisms for inserting and removing the electronic circuit unit 10. Hence, it is difficult to assure the connection of the connector securely in the conventional mechanisms for inserting and removing the electronic circuit unit 10.
Second, a shield gasket is provided around the surface board of the electronic circuit unit 10 in the vicinity of the lever 12 for inserting and removing, so as to shield leakage of the electromagnetic wave from the electronic circuit unit to the outside. In a case where an attempt is being made to connect the electronic circuit unit 10 to the shelf 20 by the lever 12 for inserting and removing, the electronic circuit unit 10 is at first manually pushed to be inserted. And then, the lever 12 for inserting and removing is rotated counterclockwise to connect the electronic circuit unit 10 to the shelf 20, as the operator feels a resistant force (an elastic force) against the insertion of the electronic circuit unit 10, which is caused by the contact to the shield gaskets of neighboring electronic circuit units.
However, the timing when the operator feels the resistant force (the elastic force) does not always coincide with the timing when the lever 12 for inserting and removing should be rotated to connect the electronic circuit unit 10 to the shelf 20. Hence, the lever 12 for inserting and removing is rotated in error before the electronic circuit unit 10 is positioned to start being connected to the shelf 20. That is, it is difficult for the operator to determine to start connecting the electronic circuit unit 10 to the shelf 20 by rotating the lever 12 for inserting and removing, due to the resistant force (the elastic force) of the shield gasket. Because of this, it is not possible to securely connect the electronic circuit unit 10 to the shelf 20 by rotating the lever 12 for inserting and removing.
Accordingly, it is a general object of the present invention to provide a novel and useful mechanism for inserting and removing an electronic circuit unit, in which one or more of the problems described above are eliminated.
Another and more specific object of the present invention is to provide a mechanism for inserting and removing electronic circuit units wherein connectors of the electronic circuit units are connected to connectors of the back boards securely.
The above objects of the present invention are achieved by a mechanism for inserting and removing electronic circuit units against a shelf of an electrical device where the electronic circuit units are installed, wherein the shelf includes a groove forming part, the electrical circuit unit includes a rotatable lever having a head end where a fixing part is provided; a rotatable stopper connected to the lever and having a head end where an engaging part is provided; and a housing member housing the lever and the stopper where an engaging surface engaging with the engaging part of the stopper is provided inside thereof, the electrical circuit unit is locked with the shelf by rotating the lever so as to engage the groove forming part of the shelf with the engaging part of the stopper, and the engagement between the engaging surface of the housing member and the engaging part of the stopper is not off even if a force to lift the lock is applied to the electrical circuit unit.
According to the above mentioned invention, the fixing part of the lever is fixed to the groove forming part of the shelf by rotating the lever so that the electrical circuit unit is locked with the shelf. Even if the force to lift the lock is applied to the electrical circuit unit, the engagement between the engaging surface of the housing member and the engaging part of the stopper is not off (not terminated). Hence, it is possible to accomplish locking by the lever not having play and thereby securely connect with a connector having even a short connection length.
The housing member may further include a rotation stopping part, and the lever cannot be moved, after the lever is further rotated so that the lever comes in contact with the rotation stopping part.
According to the above mentioned invention, when the lever comes in contact with the rotation stopping part, the lever cannot be further rotated. Therefore, further leverage applied to the lever cannot work so as to prevent damages based on the connection between the connector of the electronic circuit unit and the connector of the back board wiring board of the shelf.
The housing member may further include an engaging lifting guide surface, and the engaging part of the stopper may be guided on the engaging lifting guide surface by rotating the stopper and then the lever may be rotated, so that the lock between the electrical circuit unit and the shelf is off.
According to the above mentioned invention, it is possible to rotate the stopper with a light force. Hence, it is possible to lift the lock between the electrical circuit unit and the shelf by a simple operation.
The above object of the present invention is achieved by a mechanism for inserting and removing electronic circuit units against a shelf of an electrical device where the electronic circuit units are installed, wherein the shelf includes a groove forming part, the electrical circuit unit includes a rotatable lever having a head end where a fixing part is provided; a rotatable stopper connected to the lever and having a head end where an engaging part is provided; and a housing member housing the lever and the stopper where a projection part fixing an insertion guide surface where the engaging part is guided to the stopper by rotating the lever is provided inside thereof, and if a designated force is applied to the lever, the lever is rotated and the fixing part of the lever is engaged with the groove forming part of the shelf, and fixing of the stopper by the projection part of the housing member is lifted so that the engaging part of the stopper comes in contact with the insertion guide surface.
According to the above mentioned invention, fixing of the stopper is lifted. And thereby, the stopper slides on the projection part, the engaging part of the stopper moves in a direction of the insertion guide surface, and the lever is rotated. Therefore, the operator can easily determine visually when lock operation by rotating the lever with his finger can be started.
The stopper may further include another groove forming part, and the stopper may be fixed to the projection part by engaging the other groove forming part with the projection part of the housing member.
According to the above mentioned invention, it is possible to engage the groove forming part of the stopper with the projection part of the housing member securely, so that the stopper can be fixed securely.
Other objects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings.